Energy for the Biosphere

Recall: 100% 50% 1% 99% (eventually)

2. transformed into sugars by organisms containing chlorophyll via photosynthesis 3. sugars transformed to ATP by all organisms via fermentation and/or respiration Heat at every step! The sun produces radiant energy via nuclear fusion of H > He atoms

Sun’s energy moves into biosphere via Photosynthesis Chemcial nrg of organic molecules Radiant energy products reactants

Psn occurs in the leaves, cells of which contain chlorophyll and other pigments 1 2 5 6 3 4 9 & 10 7 7 8 8 Tree animation

Pigments absorb wavelengths of visible light energy, energizing pigment electrons, potential energy to be converted to the chemical energy of sugar The light that is not absorbed passes right through the leaf – its transmitted . We see these wavelength colors plants are green!

Chromatography results

6 6 6 CO2 + H2O -> C6H12O6 + O2 The overall reaction: Glucose used by source stored (potential nrg) passed on in eating # molecules required • Matter is not created or destroyed • So atoms in = atoms out Equation must be balanced ex: 6C in in CO2 = 6C in glucose

(The details!) Photosynthesis is a complex metabolic pathway – many steps!

Glucose in the form of… simple sugars starchy seeds cellulose ‘fiber’

Glucose used in Respiration by animals by plants themselves * plants don’t do photosynthesis for animals!

Respiration Plant glucose taken in (directly or indirectly) via digestion Glucose transformed to ATP - useable energy - in cells

6 6 6 O2 + C6H12O6 -> CO2 + H2O 38 ATP The overall reaction No O2? Fermentation/lactic acid pathways 4 ATP made 38 ATP Transformed glucose nrg Used to do cell work

ATP? - Adenosine Triphosphate 7.3kcal/mol Not a happy molecule Add 1st Pi  Kerplunk! Big negatively charged functional group Add 2nd Pi  EASY or DIFFICULT to add? DIFFICULT takes energy to add = same charges repel  Is it STABLE or UNSTABLE? UNSTABLE = 2 negatively charged functional groups not strongly bonded to each other So if it releases Pi  releases ENERGY Add 3rd Pi  MORE or LESS UNSTABLE? MORE = like an unstable currency • Hot stuff! • Doesn’t stick around • Can’t store it up • Dangerous to store = wants to give its Pi to anything Potential energy in the bonds of the phosphates negative to negative repel bonding of 3rd PO4 is most unstable, therefore most potential energy ATP kcal used to do cellular work

Glucose metabolized in respiration, used to bind P to ADP making higher energy ATP Potential energy of the third phosphate moved to & used where its needed ADP and Pi are recycled

Cell reproduction Building needed molecules Muscle contraction Concentrating molecules Movement = Homeostasis

(The details!)

One energy transformation you can always count on: heat Always some energy transformed into heat Heat is a dead end: little use; lost to universe in time Therefore, although energy is conserved, the system needs the constant input from the sun Heat at every step!

In Sum Energy moves into the biosphere via the photosynthesis and respiration reactions In photosynthesis, radiant energy of the sun is transformed into the chemical energy of glucose In respiration, the chemical energy of glucose is transformed into the chemical energy of ATP in cells In every energy transformation, some is converted into unusable heat O2 and CO2 are exchanged in the processes: the reactants of one are the products of the other The purpose (and a final product) is the production of ATP for cellular work: moving muscles, transmitting impulses along nerves, building molecules and tissues, etc.